Sonoluminescence is the term used for light emitted by a small bubble at the anti-node of a wave. The light pulses are extremely short, as is the wavelength of light emitted. It is believed that the temperature within these bubbles is great enough to be harnessed into nuclear fusion, although to my knowledge this hasn't been accomplished to date (in either individual or repeated trials)

Professor Rusi Taleyarkhan said that he had gotten nuclear fusion to take place, because he had detected neutrons being emitted, supposedly, from his sonoluminescence setup.

One thing that is usually used to disprove nuclear fusion claims is a lack of neutrons being produced by the reaction. Professor Taleyarkhan had used a neutron source, though to create the bubbles in the first place. It turns out that the flashes of light are on the order of a picosecond (one trillionth of a second)...he was measuring the reflected/scattered neutrons from his own source with an accuracy of a microsecond. Which is such a long span of time that it allowed the neutrons from his own source to be reflected back, and be counted as having come from the reaction, when they had not.

It has essentially been dissproven so far that he actually had nuclear fusion. I would have liked to see him run the same setup with a laser...or something else to make the bubbles. I don't know why he had to use a neutron source when he was trying to detect neutrons.